1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly, to a liquid crystal display panel with improved color reproducibility, and a method for fabricating the same.
2. Discussion of the Related Art
Liquid crystal display devices (LCDs) control light transmittance of liquid crystal cells, arranged in a matrix, according to a video signal to enable the liquid crystal cells to display an image corresponding to the video signal on a liquid crystal display panel. In order to display images, liquid crystal display devices (LCDs) include a liquid crystal display panel, where liquid crystal cells are arranged in the form of an active matrix, and a driving circuit to drive the liquid crystal panel.
FIG. 1 is a sectional view illustrating a related art liquid crystal display panel 90.
As shown in FIG. 1, the liquid crystal display panel 90 includes a color filter array substrate 70 which consists of a black matrix 4, a color filter 6, a common electrode 18 and an upper alignment layer 8 formed in this order on an upper substrate 2. The liquid crystal display panel 90 also includes a thin film transistor array substrate 80 which consists of a thin film transistor 7, a pixel electrode 16, and a lower alignment layer 38 arranged on a lower substrate 32. The liquid crystal display panel 90 also includes liquid crystal material 52 interposed in the space between the color filter array substrate 70 and the thin film transistor array substrate 80.
In the color filter array substrate 70, the black matrix 4 helps to prevent light leakage and increase contrast by absorbing external light. The color filter 6 consists of red (R), green (G), and blue (B) (blue not illustrated) filters, which produce red, green and blue colors, respectively. The common electrode 18 receives a common voltage and contributes to controlling the motion of liquid crystals. At least a spacer 13 maintains the cell gap between the color filter array substrate 70 and the thin film transistor array substrate 80.
In the thin film transistor array substrate 80, the thin film transistor 7 includes: a gate electrode 9 arranged together with a gate line (gate line not shown) on the lower substrate 32, semiconductor layers 14 and 47 overlapping the gate electrode 9 and a gate insulating film 44 that is beneath the semiconductor layers 14 and 47; and a source electrode 40 and a drain electrode 42 arranged together with the gate line (gate line not shown) between the semiconductor layers 14 and 47. The thin film transistor 7 supplies a pixel signal through a data line to a pixel electrode 16, in response to a scanning signal through the gate line. The pixel electrode 16 may be made of a transparent conductive material with high light-transmittance and is in electrical contact with the drain electrode 42 of the thin film transistor 7 through a passivation film 50. Upper and lower alignment layer 8 and 38 aid in the alignment of liquid crystal and may be formed by application of an alignment material such as polyimide, followed by a step of rubbing, for example.
FIG. 2A through and including 2F are sectional views sequentially illustrating a method for fabricating a color filter array substrate of a related art liquid crystal display panel.
First, an opaque resin is applied to an upper substrate 2 by deposition such as sputtering, and is then patterned by photolithographic and etching processes using a first mask, to form a black matrix 4, as shown in FIG. 2A. The black matrix 4 may be composed of a material such as chrome (Cr), for example.
A red color resin is deposited on the upper substrate 2 including the black matrix 4, and is then patterned by photolithographic and etching processes using a second mask, to form a red color filter R, as shown in FIG. 2B.
A green color resin is deposited on the upper substrate 2 including the resulting structure, and is then patterned by photolithographic and etching processes using a third mask, to form a green color filter G, as shown in FIG. 2C. A blue color resin is deposited on the upper substrate 2 including the resulting structure, and is then patterned by photolithographic and etching processes using a fourth mask, to form a blue color filter B, as shown in FIG. 2D. As a result, red, green and blue color filters 6 are formed.
A transparent conductive material is deposited over the entire surface of the upper substrate 2 including red, green and blue color filters, to form a common electrode 18, as shown in FIG. 2E.
An organic or inorganic insulating material is deposited on the upper substrate 2 including the common electrode 18 and is then patterned by photolithographic and etching processes using a fifth mask, to form column spacers 13, as shown in FIG. 2F.
As such, at least five mask processes are required for the fabrication of the color filter array substrate 70 of the related art liquid crystal display panel 90. Each of the mask processes includes a photolithographic process, which is a photographic process involving a series of steps including application of a photoresist, mask alignment, light exposure and development. Such a photolithographic process requires a lot of time, consumes a tremendous amount of developing solution used to develop the photoresist and patterns thereof, and requires expensive equipment such as exposure equipment, thus disadvantageously making a liquid crystal display panel fabrication process time consuming, complex and expensive.